LED has bid farewell to the era of high profits

Whether it is a power supply with current limiting constant current control or a constant current power supply controlled by an op amp, the power supply problem must be solved. That is, when the switching power supply chip is working, a relatively stable DC voltage is required to supply power to the chip, and the operating current of the chip varies from one MA to several MAs. There is a kind of FSD200, NCP1012, and HV9910. This kind of chip is high-voltage self-feeding. It is convenient to use, but high-voltage feeding causes the IC heat to rise because the IC has to withstand about 300V DC, as long as it has a little current. Even if it is an MA, it has zero damage of zero watts. Generally, the LED power supply is only about ten watts. If you lose a few watts, you can pull down the efficiency of the power supply by a few points. There is also a typical like QX9910. Use the resistor to pull down the power, so that the loss is on the resistor, and it will lose about a few watts. There is also magnetic coupling, which is to use a transformer to add a winding to the main power coil, just like the auxiliary winding of the flyback power supply, so as to avoid losing the power of a few watts. This is one of the reasons why I don't isolate the power supply and use the transformer. In order to avoid losing the power of a few watts, I will increase the efficiency by a few points.